CA IDMS Buffer Tuning
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This document contains a presentation on tuning database and journal buffers in CA IDMS. The presentation covers defining and sizing database and journal buffers, how buffers work, improving zIIP usage through buffer tuning, and recovery considerations. It includes steps for defining and changing database buffers, defining journal buffers, and recommendations for tuning buffers to reduce I/O and help recovery performance.
CA IDMS Buffer Tuning
- 2. 2 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD © 2016 CA. All rights reserved. All trademarks referenced herein belong to their respective companies. The content provided in this CA World 2016 presentation is intended for informational purposes only and does not form any type of warranty. The information provided by a CA partner and/or CA customer has not been reviewed for accuracy by CA. For Informational Purposes Only Terms of this Presentation
- 5. 5 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Defining a Database Buffer § Bullet 1, Calibri regular 24 pt – Sub-bullet, Calibri regular 20 pt § Sub-sub-ullet, Calibri regular 18 pt – Sub-sub-sub Bullet, Calibri regular 16 pt § Sub-sub-sub-sub Bullet, Calibri regular 16 pt
- 41. 41 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Journal I/O Error on RBN 100 § Stop Journaling § Set High RBN to 99 § Swap to the next journal § CA IDMS™ takes journal buffers for RBN 100 – 107 and writes to the new journal § Restart journaling
- 42. 42 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Journal I/O Error on RBN 100 § When recovery, either automatic recovery or warmstart, or the Archive Journal reads the old journal, it will stop at RBN 99 § They will not read RBN 100 § Even though RBN 102, 103 and 105 were successfully written to the old journal, the high RBN of 99 will stop CA IDMS from accessing RBNs 102, 103 and 105
- 44. 44 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD DCMT Display Buffer § If you have 8 journal buffers, and all are waiting for I/O, the 9th transaction will wait for a journal buffer. § This shows up on a DCMT Display Buffer, or DCMT Display Buffer journal- buffer as: Waits 1
- 45. 45 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Journal Buffer and I/O § If the Wait count is anything but ‘0’, then add buffers to the journal buffer § An additional 1 or 2 make a tremendous difference
- 46. 46 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Journal I/O § If Waits on Prior I/O is high, then the bottleneck is most likely the journal itself § The I/O is taking too long - adding buffers to the Journal Buffer will NOT help the situation § Talk to the system’s group, and see if the I/O speed to the journal can be improved
- 49. 49 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Journal Buffer Pool Recovery § Recovery will look in the journal buffers first, to see if the journal images are still in the buffers § If there are more journal images that are not in the buffers, CA IDMS will read the journal backwards § Most DASD is Cached at the device level – Cache works like a buffer pool however, it is built to work in a forward direction, not backwards like recovery – Warmstart will read the journal backwards – Make sure applications issue commits, so warmstart does not have to read many blocks backwards
- 50. 50 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD zIIP Processing § The only processing done in TCB mode is: – I/O, SVC execution, and User Mode code § ADS, COBOL, DB Procedures, SYSTEM Exits § All other processing is done on the specialty processor (zIIP) § By reducing I/O, you will increase zIIP utilization § Increase Database Buffers where possible
- 51. 51 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Summary § Increase Database buffers to reduce I/O § Increase Journal buffers to help recovery § Reducing I/O will help zIIP processing
- 52. 52 © 2016 CA. ALL RIGHTS RESERVED.@CAWORLD #CAWORLD Recommended Sessions SESSION # TITLE DATE/TIME MFX100S Strategy and Vision for CA IDMS 11/16/2016 at 12:45 pm MFX101S Legacy is not a Dirty Word 11/16/2016 at 1:45 pm MFX102S CA IDMS 19.0 Web Services for Modernization 11/16/2016 at 3:00 pm MFX103S CA IDMS 19.0 SQL Enhancements for Modernization 11/16/2016 at 3:30 pm MFX104S Java Access to CA-IDMS Data at BT (British Telecom) 11/16/2016 at 4:45 pm MFX105S Implementation and Use of Generic VTAM Resources with Parallel SYSPLEX Features (CA and CAXIA) 11/17/2016 at 12:45 pm MFX106S CA IDMS Buffer Tuning 11/17/2016 at 1:45 pm MFX107S M3A Services Monitor, Measure, Manage and Alert 11/17/2016 at 3:00 pm MFX108S Birds of a Feather/Stump the Techie! 11/17/2016 at 3:45 pm